Swiss FEL is a free electron laser(FEL) under commissioning at the Paul Scherrer Institut(PSI) in Switzerland. Digital low-level RF(LLRF) systems are used in Swiss FEL to control more than 30 RF stations with either s...Swiss FEL is a free electron laser(FEL) under commissioning at the Paul Scherrer Institut(PSI) in Switzerland. Digital low-level RF(LLRF) systems are used in Swiss FEL to control more than 30 RF stations with either standing wave cavities(e.g. RF gun) or travelling wave structures working at different frequencies. After conditioned to desired power levels, the RF stations need to be setup for beam operation and the LLRF parameters need to be optimized for maximizing the beam stability. Several beam-based algorithms were developed to facilitate the setup, calibration and optimization of the Swiss FEL RF stations for beam operation. The algorithms were implemented as automation procedures in the framework of Experimental Physics and Industrial Control System(EPICS) and were used in commissioning and daily operation of Swiss FEL. In this paper, the algorithms and the implementation will be introduced together with the test results during the commissioning of SwissFEL.展开更多
Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should b...Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should be better than 5µm under 450 kg load of sextupoles.The movement range is required to be±0.3 mm in both horizontal direction and vertical direction.And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz.Purpose The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness.And to find the difficulties of development of this mover.Method Interferometer is used to measure the motion accuracy,and pressure accelerometer is used to test the mover equivalent stiffness.Combining with the actual measurement results of equivalent stiffness,the natural frequency of the magnet support system is simulated.Result The motion accuracy reaches to 5.3µm in vertical direction and 1µm in horizontal direction,respectively.The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system.Unwanted movement coupling has occurred during the mover exercises in vertical direction.Conclusions Through the research of experimental mover prototype,the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load.However,further researches and improvements are necessary to fix the coupling error during the vertical movement.展开更多
Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-b...Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.展开更多
文摘Swiss FEL is a free electron laser(FEL) under commissioning at the Paul Scherrer Institut(PSI) in Switzerland. Digital low-level RF(LLRF) systems are used in Swiss FEL to control more than 30 RF stations with either standing wave cavities(e.g. RF gun) or travelling wave structures working at different frequencies. After conditioned to desired power levels, the RF stations need to be setup for beam operation and the LLRF parameters need to be optimized for maximizing the beam stability. Several beam-based algorithms were developed to facilitate the setup, calibration and optimization of the Swiss FEL RF stations for beam operation. The algorithms were implemented as automation procedures in the framework of Experimental Physics and Industrial Control System(EPICS) and were used in commissioning and daily operation of Swiss FEL. In this paper, the algorithms and the implementation will be introduced together with the test results during the commissioning of SwissFEL.
文摘Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should be better than 5µm under 450 kg load of sextupoles.The movement range is required to be±0.3 mm in both horizontal direction and vertical direction.And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz.Purpose The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness.And to find the difficulties of development of this mover.Method Interferometer is used to measure the motion accuracy,and pressure accelerometer is used to test the mover equivalent stiffness.Combining with the actual measurement results of equivalent stiffness,the natural frequency of the magnet support system is simulated.Result The motion accuracy reaches to 5.3µm in vertical direction and 1µm in horizontal direction,respectively.The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system.Unwanted movement coupling has occurred during the mover exercises in vertical direction.Conclusions Through the research of experimental mover prototype,the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load.However,further researches and improvements are necessary to fix the coupling error during the vertical movement.
基金supported by the National Natural Science Foundation of China(No.11975227)。
文摘Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.
